2 KIO3 (aq) + 6 H2O2 (aq) + Cl2 (g) → I2 (s) + 2 KCl (aq) + 6 O2 (g) + 6 H2O (l)
This is an oxidation-reduction (redox) reaction:
2 IV + 10 e- → 2 I0 (reduction)
2 Cl0 + 2 e- → 2 Cl-I (reduction)
12 O-I - 12 e- → 12 O0 (oxidation)
KIO3 is an oxidizing agent, Cl2 is an oxidizing agent, H2O2 is a reducing agent.